Is nocturnal polyuria the reason you are on the loo all night?

You’ve likely heard of nocturia, but have you heard of nocturnal polyuria? This is a condition where we overproduce an excessive volume of urine at night, often leading to constant wakings through the night for the loo.

When nocturnal polyuria occurs, our body’s natural rhythm of urine production is disrupted. Ideally, we should produce less urine at night, allowing us to sleep undisturbed. In cases of nocturnal polyuria, however, this rhythm is altered due to increased kidney activity at night. The kidneys filter excess water from our bloodstream and process it as urine, filling our bladders more quickly than usual during the night.

Though it’s common for us to experience the need to pee during the night, if you are finding that your bladder is constantly making you dash for the loo then it could be due to this overproduction of urine. For those of us dealing with it, understanding the causes and options for managing it can make a difference in our daily lives.

What is the difference between nocturia and nocturnal polyuria?

When it comes to night-time bladder issues, we often hear two terms: nocturia and nocturnal polyuria. Though they sound similar, they represent different issues.

• Nocturia is the need to wake up multiple times in the night to urinate. It doesn’t necessarily mean we’re producing excessive urine, just that our bladder prompts us to go. Nocturia can result from hormonal changes, lifestyle factors (such as caffeine or alcohol), or even certain medications.

• Nocturnal Polyuria is when we produce an abnormally high volume of urine at night, rather than throughout the day. This is often measured by looking at the total volume of urine produced overnight, which, in cases of nocturnal polyuria, is more than a third of what you produce during the day. Because of this, nocturnal polyuria has unique underlying causes and requires specific management strategies.

What symptoms should you look out for?

Here are the key symptoms of nocturnal polyuria:

• Producing an excessive volume of urine at night, often more than a third of total daily urine output

• Frequently waking up during the night to urinate, leading to sleep disruption

• Experiencing increased urgency and volume of urine output specifically at night, even if daytime urination seems normal

• Waking up feeling tired due to frequent interruptions in sleep

• Possible swelling or fluid retention in the legs during the day that redistributes at night

Nocturnal polyuria becomes increasingly common as we age. Both men and women can experience NP, and many of us may notice this overproduction as we enter menopause due to changes in our hormones. 

Other factors that can cause polyuria

In the first instance, you should speak with your GP if you think that you are experiencing any of the symptoms in the list above. Your doctor will consider a number of factors:

1. Hormonal Shifts

Hormones such as vasopressin, which regulates the body’s water balance, typically signal our kidneys to retain more water overnight, so we don’t need to urinate as often. However, as we age, this hormone’s effect can diminish, leading to greater urine production during sleep. Menopausal shifts can also alter hormone levels, adding to the condition's prevalence in midlife and beyond.

2. Cardiovascular Health

Conditions such as heart failure or high blood pressure may lead to fluid retention in the lower body during the day. When we lie down at night, this fluid redistributes and may increase urine production as the kidneys process the excess fluid. This is why, for some of us, nocturnal polyuria can be linked to broader circulatory issues.

3. Kidney Function Changes

Our kidneys may lose some of their filtering efficiency as we age. This change can lead to an increased amount of sodium and water being processed overnight, contributing to nocturnal polyuria. If our kidneys are not efficiently concentrating urine, more frequent night-time trips may result.

4. Sleep Apnoea

Sleep apnoea, a common sleep disorder, is also associated with nocturnal polyuria. When sleep apnoea disrupts breathing, it can prompt a series of biological responses, including increased production of atrial natriuretic peptide, a hormone that increases urine output. If we experience this condition, addressing sleep apnoea may help reduce night time urination as well.

5. Medications

Certain medications, including diuretics, can contribute to nocturnal polyuria. Diuretics, in particular, prompt the kidneys to expel more water and salt, which can lead to increased urination at night. If you’re on such medications and experiencing nocturnal polyuria, you should speak to your GP or urologist to discuss your dose.

A few things you can try to ease nocturnal polyuria

Your doctor may prescribe medication to help you manage the production of urine at night and ease the number of wakings to pee that you experience. There are some lifestyle changes you can try too, to lessen the impact of nocturnal polyuria. 

Be mindful of your fluid intake a night

Keeping a bladder diary can help to monitor your fluid intake. You may benefit from reducing your fluid intake before bed - and try to sip, not gulp drinks in the evening as this helps your bladder to gently process fluid. 

Reduce your salt intake in your evening meal

Salt (sodium) intake can influence how much water we retain in our bodies. Reducing salty snacks or heavily salted meals in the evening can reduce water retention and, by extension, the amount of urine produced at night.

Increase your daily movement and elevate your legs

If fluid retention in your legs is a concern, engaging in light exercise throughout the day can help prevent it, such as walking, yoga, or swimming. Additionally, elevating your legs for 30 minutes in the late afternoon can encourage fluid redistribution, reducing its effect at night.